The present invention is related to a process for producing fine denier fibers. More specifically, the invention is related to a process for producing fine denier split fibers.
Nonwoven and woven fabrics containing split or fibrillated fine fibers exhibit highly desirable properties, including textural, barrier, visual and strength properties. There are different known processes for producing split fine fibers, and in general, split fibers are produced from conjugate fibers which contain two or more incompatible polymer components or from an axially oriented film. For example, a known method for producing split fibrous structures includes the steps of forming splittable conjugate filaments into a fabric and then treating the fabric with an aqueous emulsion of benzyl alcohol or phenyl ethyl alcohol to split the conjugate filaments. Another known method has the steps of forming splittable conjugate filaments into a fibrous structure and then splitting the conjugate filaments by flexing or mechanically working the filaments in the dry state or in the presence of a hot aqueous solution. Yet another commercially utilized method for producing split fine denier fibers is a needling process. In this process, conjugate fibers are hydraulically or mechanically needled to separate the different polymer components of the conjugate fibers. Further yet another method for producing fine fibers, although it may not be a fiber splitting process, utilizes conjugate fibers that contain a solvent- or water-soluble polymer component. For example, a fibrous structure is produced from sheath-core conjugate fibers and then the fibrous structure is treated with a solvent that dissolves the sheath component to produce a fibrous structure of fine denier fibers of the core component.
Although different prior art processes, including the above described processes, for producing split or fibrillated fine denier fibers are known, each of the prior art processes suffers from one or more drawbacks including the use of chemicals, which may create disposal problems; a long fibrillation processing time; and/or a cumbersome hydraulic or mechanical fiber splitting process. Consequently, the prior art split fiber production processes are not highly economical and are not highly suitable for commercial scale productions. In addition, the prior art processes do not tend to produce uniformly split fibers and/or do not provide high levels of fiber splitting.
There remains a need for a production process that is economical and is not deleterious to the environment and that provides high levels of fiber splitting. Additionally, there remains a need for a, fine fiber production process that is continuous and can be used in large commercial-scale productions.